1. Field of the Invention
The present invention relates to electrolytic capacitors and, more specifically, to a capacitor with a relatively low effective surface resistance.
2. Description of the Prior Art
Recent developments in electrochemical cells have led to new types of cell-related electrochemical capacitors (ECC). As shown in FIG. 1, this type of device 100 usually includes two end plates 102, each coated whin an electro-active material 106, that sandwich a polymer electrolyte 114. An electrical connection tab 110 usually extends from each of the end plates 102.
Due to the design of the tab placements, the entire electro-active area is not completely used by the capacitor. This amount of non-use varies from one end plate material to the next. Thickness, form factor and chemistry all affect the effective surface resistance (ESR) of the endplate. Because the tabs are usually on the same end of the device, there is typically a non-uniform current flow through the device. For example, in a 4 cm by 4 cm square ECC that is 5 mil thick with 3 mil of electrolyte and two 1 mil titanium plates, at least 10% of the area of an ECC is not used to conduct charge. Furthermore, due to the highly corrosive nature of the electrolytic liquids used, many ECC""s use end plates constructed from high resistance alloys to increase reliability (some common high resistance materials tend to be more resistant to the corrosive effects of electrolytic, liquids). Thus, typical ECC""s tend to have a relatively high ESR.
Therefore, there is a reed for an electrochemical capacitor with a high capacitance and a low effective surface resistance.